I think that’s probably fair, especially if they’re currently working or volunteering for the campaign.
So what is the claim, that they’re not allowed to ask about that at all, weren’t allowed to put it on the questionnaire, weren’t allowed to ask about it in open voir dire, or just weren’t allowed to lead with it?
I think there are probably preliminary questions that could be asked to develop the relevance of political bias.
“My client is a public figure and former president of the United States. Were you familiar with him before today?” (Yes).
“Did any things you’ve learned about Mr. Trump that have caused you to form a negative opinion of him?”
If yes, they should ask for individual questioning, which the judge seems to be allowing, so they can get more into it without tainting the jury pool. If it’s political, then I would think they have a lot more leverage to go into those details about campaign work and affiliation. If it’s just his public persona, then politics are less relevant.
I’d be surprised if the Judge is saying they can’t, under any circumstances, get into the jurors’ politics, because that would be a bad ruling and, IMO, would be evidence of bias.